A power generator using a conventional polymer electrolyte fuel cell will be explained below by using a block diagram in FIG. 5. In FIG. 5, reference numeral 1 denotes a fuel cell section and a fuel processing apparatus 2 performs steam reforming on raw materials such as natural gas, generates a gas whose main component is hydrogen and supplies the gas to the fuel cell 1. The fuel processing apparatus 2 is provided with a reformer 3 that generates a reformed gas and a carbon monoxide transformer 4 that allows carbon monoxide contained in the reformed gas to react with water to form carbon dioxide and hydrogen. A fuel side humidifier 5 humidifies a fuel gas to be supplied to the fuel cell 1. Reference numeral 6 denotes an air feeder that supplies air of an oxidizer to the fuel cell 1. At this time, an oxidation side humidifier 7 humidifies the supplied air. The power generator is further provided with a cooling pipe 8 through which water is sent to the fuel cell 1 for cooling, a pump 9 that circulates water in the cooling pipe and a radiator unit 10 for cooling that dissipates heat generated in the fuel cell 1 to the outside.
When power is generated using such an apparatus, water is circulated by the pump 9 through the cooling pipe 8 to keep temperature of the fuel cell 1 constant and heat generated in the fuel cell 1 is dissipated to the outside by the radiator unit 10 for cooling.
However, the above-described conventional configuration dissipates heat generated in the fuel cell 1 to the outside using the heat dissipation fan including a radiator unit 10 for cooling, and therefore cannot utilize heat generated during power generation, which results in a problem of failing to construct a cogeneration apparatus.
The conventional configuration also has a problem that it is unable to utilize waste heat of waste air or waste fuel gas after reaction in the fuel cell 1.
Furthermore, when power is generated using a cogeneration apparatus that generates a fuel gas from raw materials such as natural gas, the reformed gas after being transformed by the carbon monoxide transformer 4 contains a small quantity of carbon monoxide as remains. In such a situation, it is necessary to operate the apparatus within a predetermined temperature range in order to prevent the polymer electrolyte fuel cell 1 from being poisoned with carbon monoxide. However, the above-described power generator has no means of adjusting water temperature of the cooling circuit; therefore, it has problems that it is difficult to adjust temperature of the fuel cell 1, such as maintaining temperature of the fuel cell 1 during a low load operation and difficult to maintain performance of the fuel cell 1.